Storage Phosphor Layer and System and Method for Erasing Same

ABSTRACT

An apparatus ( 1 ) for erasing a storage phosphor layer ( 2 ) includes a radiation source ( 8 ) for producing and emitting erasing radiation, a drive ( 5 ) for producing a relative movement between the storage phosphor layer ( 2 ) and the radiation source ( 8 ), the storage phosphor layer ( 2 ) lying or being moved in a holding plane ( 7 ), and a reflector ( 11 ) for reflecting radiation. The reflector ( 11 ) is arranged and designed to reflect erasing radiation reflected by the storage phosphor layer ( 2 ) in the direction of the storage phosphor layer ( 2 ). A further reflecting surface ( 31 ) is provided for reflecting erasing radiation which is positioned opposite the reflector ( 11 ), as considered in a direction at right angles to the direction ( 6 ) of the relative movement.

RELATED APPLICATIONS

This application claims priority to European Patent Application No.EP06119939.4, filed on Aug. 31, 2006, which is incorporated herein byreference in its entirety.

This application relates to U.S. Application Publication No. [AttorneyDocket No. 0119.0080US1 (HEMN06006)], filed on even date herewith,titled “Storage Phosphor Layer and System and Method for Erasing Same,”by Dr. Andreas Bode et al, and U.S. Application Publication No.[Attorney Docket No. 0119.0082US1 (HEMN06008)], filed on even dateherewith, titled, “Storage Phosphor Layer and System and Method forErasing Same,” by Dr. Andreas Bode et al

BACKGROUND OF THE INVENTION

Apparatuses for erasing a storage phosphor layer with a radiation sourcefor producing and emitting erasing radiation are used in particular inthe field of computer radiography (CR) for medical purposes. A pictureis produced of an object, for example a patient or a body part of thepatient, by means of X-ray radiation. The picture is stored in a storagephosphor layer as a latent picture. Therefore, this type of X-raypicture contains X-ray information about the object. In order to readout the X-ray information stored in the storage phosphor layer, thestorage phosphor layer is stimulated by means of an irradiation device.As a result of this stimulation the storage phosphor layer emitsradiation that has an intensity corresponding to the X-ray informationstored in the storage phosphor layer. The radiation emitted by thestorage phosphor layer is collected by a detection device and convertedinto electrical signals, which contain an image of the X-rayinformation. The electrical signals are further processed and the X-rayinformation stored in the storage phosphor layer is then made visible.The X-ray information can be displayed directly on a monitor, forexample, or be written onto a photographic X-ray film by means of aprinter used especially for X-ray pictures.

After reading out the X-ray information from the storage phosphor layer,remains of the latent picture remain in the latter. Furthermore, noiseinformation can be stored in the layer. In order to be able to use thestorage phosphor layer for further X-rays, it is important to erase thisinformation. For this procedure, a radiation source is used that emitserasing radiation onto the storage phosphor layer. An apparatus forerasing a storage phosphor layer is known from U.S. Pat. No. 7,075,200B2. As a radiation source, this erasing apparatus contains two lineswith light emitting diodes, disposed parallel to one another, foremitting the erasing radiation. For erasure, the storage phosphor layeris pushed in a direction of conveyance through a ray path of the linesof light emitting diodes. The two lines of light emitting diodes areintegrated with reflectors which are spaced apart from one another. Thereflectors serve to reflect erasing radiation emitted by the lightemitting diodes in the direction of the storage phosphor layer. Thereflectors have a groove-shaped cross-sectional surface with obtuseinner angles so that the groove-shaped profile of the reflectors opensfrom the light emitting diode arrangement in the direction of thestorage phosphor layer. The width of the reflectors here in thedirection of conveyance is adapted to their function of guiding theradiation of the erasing radiation emitted by the light emitting diodes.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for erasing a storagephosphor layer with a radiation source for producing and emittingerasing radiation, a drive for producing a relative movement between thestorage phosphor layer and the radiation source, the storage phosphorlayer lying or being moved in a holding plane, and a reflector forreflecting radiation. The present invention further relates to a systemwith this type of apparatus and a storage phosphor layer.

It is the object of the present invention to enable high efficiency whenerasing a storage phosphor layer.

According to the invention, the reflector is arranged and designed toreflect erasing radiation reflected by the storage phosphor layer in thedirection of the storage phosphor layer. A further reflecting surface isprovided for reflecting erasing radiation which is positioned oppositethe reflector, as considered in a direction at right angles to thedirection of the relative movement.

The knowledge which forms the basis of the present invention is that thestorage phosphor layer generally has a high degree of reflection. Due tothis, a large part of the erasing radiation is reflected without beingused and does not contribute to the erasure of undesired pictureinformation stored in the storage phosphor layer. Upon the basis of thepresent invention, the erasing radiation reflected by the storagephosphor layer is captured by the reflector and reflected back again inthe direction of the storage phosphor layer. This reflection can bedirected (specular) or diffuse. The erasing radiation reflected back bythe reflector can therefore also contribute to erasure of the storagephosphor layer. In this way the efficiency of the erasure issubstantially improved. Furthermore, the power requirement is less, andthis leads to less lost heat and an increase in lifespan. Furthermore,it can be presumed that the failure rate will be reduced. Ifappropriate, in this way one can dispense with cooling of the radiationsource. This guarantees a cost-effective erasing apparatus. Furthermore,less space is often required. The design of the reflector canadvantageously be adapted simply to the type and form of the storagephosphor layer. In particular, the reflector is arranged such that itincludes at least one reflection surface which faces towards the holdingplane. It can advantageously have reflecting layers on the reflectorsurface facing towards the holding plane. In this way the degree ofreflection can be perceptibly improved. Advantageously, by means of thisfurther reflecting surface, at the start and/or at the end of theerasing process, i.e. when the ray path of the radiation source is notor not fully directed at the storage phosphor layer, the erasingradiation emitted by the radiation source can be reflected by thefurther reflecting surface in the direction of the reflector. Theerasing radiation reflected by the further reflecting surface which inparticular has not yet reached the storage phosphor layer, can thereforebe directed by the reflector towards the storage phosphor layer. Inparticular, the front, and if applicable, the rear edge of the storagephosphor layer can therefore be erased with a high level of efficiency.The further reflecting surface can be designed such that the erasingradiation is reflected directionally (specularly) or diffusely.

Preferably, the further reflecting surface is disposed on the side ofthe holding plane facing away from the reflector. In this way, it can beparticularly well guaranteed that erasing radiation not hitting thestorage phosphor layer is reflected by the further reflecting surface soas to then be reflected by the reflector in the direction of the storagephosphor layer.

Particularly preferably, the further reflecting surface has a width inthe direction of the relative movement which is at least as great asthat of the reflector. In this way it can be guaranteed that forms ofthe further reflecting surface and of the reflector correspondparticularly well to one another. A particularly large quantity oferasing radiation emitted by the radiation source can be reflected bythe further reflecting surface, and a large quantity of this reflectederasing radiation is reflected by the reflector in the direction of thestorage phosphor layer. In this way, a particularly high level oferasing efficiency can be achieved.

Particularly preferably, a width of the reflector in the direction ofthe relative movement is at least ten times as great as a smallestdistance between the reflector and the holding plane. By means of thisdimensioning of the reflector with its large width in the direction ofthe relative movement and its distance from the holding plane, it canadvantageously be guaranteed for the storage phosphor layer that a largepart of erasing radiation reflected or dispersed by the storage phosphorlayer can be captured or collected and reflected back again in thedirection of the storage phosphor layer.

In one advantageous embodiment of the invention, the reflector has aflat reflector surface which extends parallel to the holding plane. Thistype of reflector form can reliably reflect reflected erasing radiationback to the storage phosphor layer. This form of reflector can bemanufactured cheaply and can be compact in design.

In a further advantageous embodiment the reflector has a reflectorsurface with a structure. With this type of structure the efficiency ofthe erasure can be even further increased. The structure can inparticular be fluted, or in the form of a roof or saw teeth, triangularetc. Particularly preferably, the structured reflector surface can beretroreflective in form so that it reflects back at least part of theerasing radiation dispersed back by the storage phosphor layer to thesame points of the storage phosphor layer. This type of retroreflectivereflector surface guarantees particularly efficient erasure of thestorage phosphor layer. At those points that have dispersed andreflected a lot of erasing radiation, a lot of erasing radiation is alsoreflected back. The retroreflective reflector surface can in particularbe designed in the form of a so-called “cat's eye”, and be inserted forexample as a film. This is particularly space saving and cost-effective.

Particularly advantageously, the reflector has at least two reflectorsurfaces so that the reflector, considered in the direction of therelative movement, is formed to either side of the radiation source. Inthis way, a particularly large amount of erasing radiation can becollected and reflected back. Here, the reflector can in particular beformed with mirror- or reflection-symmetrically in the direction of therelative movement, an axis of symmetry extending at right angles to thedirection of the relative movement, and as considered in the directionof the relative movement, centrally through the radiation source. Bymeans of this type of reflector, a large quantity of reflected erasingradiation can be collected to either side of the radiation source, andbe reflected back to the storage phosphor layer.

Preferably, the reflector has a groove- or trough-shaped cross-sectionalsurface. This type of reflector is particularly easy to produce andachieves a high level of efficiency when erasing. The groove- ortrough-shaped cross-sectional surface can advantageously have obtuseinner angles which are in particular greater than or equal to 130°. Inthis way the quantity of reflected erasing radiation that is reflectedback to the storage phosphor layer, is increased even further.

In one advantageous embodiment of the invention, considered in thedirection of the relative movement, reflector extension surfacesextending parallel to the holding plane adjoin both ends of the groove.Preferably, the reflector extension surfaces have structures. Theseembodiments respectively guarantee even better efficiency of the erasureprocess.

Particularly advantageously, the radiation source has at least two lineswith light emitting diodes extending at right angles to the direction ofthe relative movement and parallel to the holding plane. In this way, asufficiently high intensity of erasing radiation can be produced, thepower consumption of the light emitting diodes being particularly low.The at least two lines with light emitting diodes can preferably beintegrated into the reflector. Here, a distance between the at least twolines can advantageously be smaller than or equal to a distance betweenthe light emitting diodes and the holding plane. Due to this, thereflector, and so also the erasing apparatus can be particularly compactin design. Furthermore, the erasing radiation emitted by the lines oflight emitting diodes can be emitted and be particularly well directedat the storage phosphor layer.

Particularly preferably, a particular reflector is allocated to each ofthe at least two lines with light emitting diodes. The light emittingdiodes of the respective lines further emit radiation, in particular ina narrow-band wavelength range different to that of the light emittingdiodes of the other lines. The reflectors are designed in particular sothat they contribute to separation of the erasing radiation with thedifferent wavelength ranges emitted by the different lines of lightemitting diodes. In this way, particular spectral ranges can beprevented from mutually affecting or disrupting one another. Thewavelength ranges are advantageously chosen such that wavelengths thatdo not contribute to the erasure of the type of storage phosphor layerused are not available. Due to this, the filtering out of thesewavelengths, which would otherwise be necessary, is not necessary.Furthermore, particularly good erasing efficiency is achieved.

Preferably, the storage phosphor layer of the system according to theinvention has a degree of reflection for the erasing radiation ofgreater than or equal to 70%, and in particular greater than or equal to80%. The erasing apparatus according to the invention can be usedparticularly efficiently for storage phosphor layers with this highlevel of reflection.

The above and other features of the invention including various noveldetails of construction and combinations of parts, and other advantages,will now be more particularly described with reference to theaccompanying drawings and pointed out in the claims. It will beunderstood that the particular method and device embodying the inventionare shown by way of illustration and not as a limitation of theinvention. The principles and features of this invention may be employedin various and numerous embodiments without departing from the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, reference characters refer to the sameparts throughout the different views. The drawings are not necessarilyto scale; emphasis has instead been placed upon illustrating theprinciples of the invention. Of the drawings:

FIG. 1 shows a first exemplary embodiment of an erasing apparatusaccording to the invention with a reflector which has flat reflectorsurfaces extending parallel to a storage phosphor layer, and with afurther reflection surface positioned opposite the reflector,

FIG. 2 shows a second exemplary embodiment of an erasing apparatusaccording to the invention with a reflector which has reflector surfaceswith a triangular structure extending parallel to the storage phosphorlayer,

FIG. 3 shows a third exemplary embodiment of an erasing apparatusaccording to the invention with a groove-shaped reflector,

FIG. 4 shows a fourth exemplary embodiment of an erasing apparatusaccording to the invention with a groove-shaped reflector which hasreflector extensions to the side extending from the ends of the grooveand which extend evenly and parallel to the storage phosphor layer,

FIG. 5 shows a fifth exemplary embodiment of an erasing apparatusaccording to the invention with the groove-shaped reflector which hasreflector extensions to the side extending from the ends of the grooveand which extend parallel to the storage phosphor layer and have a finetriangular structure,

FIG. 6 shows a sixth exemplary embodiment of an erasing apparatusaccording to the invention with the groove-shaped reflector which hasreflector extensions to the side extending from the ends of the groove,and which extend parallel to the storage phosphor layer and have a crudetriangular structure,

FIG. 7 shows a seventh exemplary embodiment of an erasing apparatusaccording to the invention with a reflector which has reflectorextensions to the side extending from the ends of a small groove, andwhich extend parallel to the storage phosphor layer and have a saw-toothshaped structure, and

FIG. 8 shows an eighth exemplary embodiment of an erasing apparatusaccording to the invention with two lines of light emitting diodes whichemit light in different wavelength ranges and which respectively havetheir own reflector.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a first exemplary embodiment of an erasing apparatus 1 thatis constructed according to the principles of the present invention forerasing X-ray information which is stored in a storage phosphor layer 2of a storage phosphor plate 3. The storage phosphor plate 3 has acarrying layer 4 on which the storage phosphor layer 2 is placed. Thestorage phosphor layer 2 is preferably made up of a plurality ofphosphor particles that serve to store the X-ray information. Here, thecarrying layer 4 is a laminate that is advantageously 1-2 millimeters(mm) thick. Here, the storage phosphor plate 3 does not form part of theerasing apparatus 1, but is typically be inserted into the erasingapparatus 1 from the outside. Within the erasing apparatus 1, thestorage phosphor plate 3 is moved by means of a drive 5 in a directionof conveyance which is represented by an arrow 6. The storage phosphorplate 3 is moved within the erasing apparatus 1 in a holding plane 7 andcan be moved within this holding plane 7. Below the holding plane 7there is a support 18 on which the storage phosphor plate 3 can lie.

The erasing apparatus 1 comprises a radiation source 8 for emittingerasing radiation. The radiation source 8 here has two lines of lightemitting diodes 9 and 10 disposed parallel to one another. The lines oflight emitting diodes 9, 10 each contain a plurality of light emittingdiodes disposed next to one another. The lines of light emitting diodes9, 10 extend over the whole length of the storage phosphor layer 2. Inthe illustration according to FIG. 1, the length of the storage phosphorlayer 2 extends at right angles to the direction of conveyance 6 and inthe direction of the plane of the drawing sheet. The width of thestorage phosphor layer 2 extends in the direction of conveyance 6. Bymeans of the drive 5, the storage phosphor layer 2 is conveyed past thelines of light emitting diodes 9, 10 with even conveyance speed in thedirection of conveyance 6. In this way the storage phosphor layer 2passes through the ray paths of the lines of light emitting diodes 9,10. Alternatively, it is also possible to convey the radiation sourceinstead of the storage phosphor plate 3, the storage phosphor plate 3then not being moved in the erasing apparatus 1. In both cases arelative movement is implemented between the radiation source 8 and thestorage phosphor layer 2 lying in the holding plane 7, which hereextends in the direction of the arrow 6.

When conveying the storage phosphor plate 3, the erasing light emittedby the light emitting diodes of the lines of light emitting diodes 9, 10hits the storage phosphor layer 2. Part of the erasing light penetratesinto the storage phosphor layer 2 and erases the X-ray informationremaining in the latter following a read-out and, if applicable, anynoise that is present. Since the storage phosphor layer 2 has a degreeof reflection of at least 70%, and in particular of at least 80% for theerasing light, a large part of the erasing light is reflected by thestorage phosphor layer 2, without contributing to the erasure.

In order to achieve a high level of efficiency and a high degree ofeffectiveness when erasing, the erasing apparatus 1 according to theinvention has a reflector 11. In the present exemplary embodiment thereflector 11 has two level reflector surfaces 12 and 13 extendingparallel to the storage phosphor layer 2. Considered in the direction ofconveyance 6, the reflector surfaces 12, 13 are disposed to either sideof the radiation source 8 and are advantageously equal in size. However,it is also possible to provide just a single reflector surface on one ofthe sides of the radiation source 8. Furthermore, it is possible todesign the reflector surfaces 12, 13 as one part, or one of the twobeing smaller than the other. The reflector 11 extends over the wholelength of the storage phosphor layer 2 and, considered in the directionof conveyance 6, over a width 14. The reflector's smallest distance 15is that from the surface of the storage phosphor layer 2 located in theholding plane 7. The width 14 is at least ten times greater than thesmallest distance 15. The reflector 11 is mirror-symmetrical in form inthe direction of conveyance 6. Here, an axis of symmetry 16 extends atright angles to the direction of conveyance 6, and in relation to thewidth 14, centrally through the radiation source 8. In the presentexemplary embodiment the axis of symmetry 16 therefore extends betweenthe two lines of light emitting diodes 9, 10. The two lines of lightemitting diodes 9, 10 are integrated centrally into the reflector 11here. A distance 17 between the two lines of light emitting diodes 9, 10is advantageously smaller than or equal to a distance 32 between thelight emitting diodes and the storage phosphor layer 2 lying in theholding plane 7. On their surfaces facing towards the storage phosphorlayer 2 the reflector surfaces 12, 13 have reflecting layers that arehighly reflective for erasing light reflected by the storage phosphorlayer 2. By means of the reflector 11, erasing light that is reflectedor dispersed by the storage phosphor layer 2 is reflected back in thedirection of the storage phosphor layer 2. Due to this re-reflection itis possible for the erasing light to now penetrate into the storagephosphor layer 2 in order to erase the X-ray information.

The erasing apparatus 1 has a further reflection surface 31 positionedopposite the reflector 11, as considered in a direction at right anglesto the speed of conveyance 6. The reflection surface 31 is designed toreflect erasing light that has been emitted by the radiation source 8.If applicable, further erasing light reflected by the reflection surface31 has already been reflected by the storage phosphor layer 2 and thereflector 11. In order to reflect erasing light, the reflection surface31 is preferably in particular placed on the side of the support 18facing towards the radiation source 8, i.e. on the side of the holdingplane 7 facing away from the reflector 11. The reflection surface 31 isadvantageously applied to the support 18 as a thin layer in one example.The reflection surface 31 is therefore arranged such that the storagephosphor plate 3 is conveyed between the reflector 11 and the reflectionsurface 31. The reflection surface 31 reflects the erasing light to thereflector 11 directionally (specularly) or diffusely. Here, thereflection surface 31 is advantageously as wide in the direction ofconveyance 6 as the reflector 11. FIG. 1 shows the storage phosphorplate 3 inserted into the erasing apparatus 1. Advantageously, thereflection surface 31 guarantees that the erasing light emitted by theradiation source 8 then also contributes to the erasure with a highdegree of effectiveness if the storage phosphor plate 3 is still notfully located within the erasing apparatus 1. In particular, it isguaranteed that the leading edge of the storage phosphor layer 2 iserased with increased efficiency. The same applies when the storagephosphor plate 3 is drawn out of the erasing apparatus 1. For erasingthe storage phosphor layer 2 it is alternatively possible to leave thestorage phosphor plate 3 in the erasing apparatus 1 and to convey theradiation source 8 together with the reflector 11 and the reflectionlayer 31 positioned opposite along the storage phosphor plate 3.

FIG. 2 shows a second exemplary embodiment of the erasing apparatus 1according to the invention. The storage phosphor plate is not shownhere. The support 18 is shown over which the holding plane 7 for holdingand moving the storage phosphor plate is located. The erasing apparatus1 contains the reflector 11. Here, the latter has two reflector surfaces19 and 20 which extend parallel to the holding plane 7 and the support18. The reflector surfaces 19, each have a structure which here issubstantially triangular in form, similar to fine saw teeth. By means ofthis structure a retroreflective profile of the reflector surfaces 19,20 is created.

FIG. 3 shows a third exemplary embodiment of the erasing apparatus 1according to the invention. In this third exemplary embodiment thereflector 11 is groove- or trough-shaped. Therefore, the cross-sectionalsurface of the reflector 11 is in the shape of a groove. For this, thereflector 11 has two reflector surfaces 21, 22 in a straight line thatextend outwards at an angle from the radiation source 8 with obtuseinner angles α. The inner angles here are approx. 165°.

FIG. 4 shows a fourth exemplary embodiment of the erasing apparatus 1according to the invention. Here, the reflector 11 is also formed in theshape of a groove by means of the two reflector surfaces 21, 22 in astraight line. The inner angles α of the groove-shaped cross-sectionalsurface are approx. 110° here. The reflector 11 has reflector extensions23, 24 to the side extending from the lower ends of the groove thatextend outwards evenly and parallel to the holding plane 7 for thestorage phosphor plate.

FIG. 5 shows a fifth exemplary embodiment of the erasing apparatus 1according to the invention. Here, the reflector 11, like the reflector11 according to the fourth exemplary embodiment, is formed in the shapeof a groove by means of the two reflector surfaces 21, 22 in a straightline. The inner angles α of the groove-shaped cross-sectional surfaceare approximately 110°. The reflector 11 has reflector extensions 25, 26to the side extending from the lower ends of the groove which extendoutwards parallel to the holding plane 7 for the storage phosphor plate.Here, the reflector extensions 25, 26 to the side have a fine triangularstructure. By means of this structure a retroreflective profile of thereflector extensions 25, 26 is created.

FIG. 6 shows a sixth exemplary embodiment of an erasing apparatus 1according to the invention. The reflector 11 here largely corresponds tothe reflector of the erasing apparatus 1 according to the fifthexemplary embodiment according to FIG. 5. However, the side reflectorextensions 25, 26 here have a crude or more coarse triangular structure.By means of this structure a retroreflective profile of the reflectorextensions 25, 26 is also created.

FIG. 7 shows a seventh exemplary embodiment of the erasing apparatus 1according to the invention. Here, the reflector 11 is also formed in agroove shape by means of two reflector surfaces 21, 22 in a straightline. However, the reflector surfaces 21, 22 are shorter here than thoseof the exemplary embodiments according to FIGS. 4-6. The reflector 11has reflector extensions 27, 28 to the side extending from the lowerends of the reflector surfaces 21, 22 of the groove and that extendoutwards parallel to the holding plane 7 for the storage phosphor plate.Here, the side reflector extensions 27, 28 have a crude or coarsesaw-tooth shaped structure with only a small number of saw teeth. Bymeans of this structure a retroreflective profile of the reflectorextensions 27, 28 is also created.

FIG. 8 shows an eighth exemplary embodiment of the erasing apparatus 1according to the invention. In this eighth exemplary embodiment theradiation source 8 contains the two lines of light emitting diodes 9, 10which here, however, each have their own reflector. The line of lightemitting diodes 9 is integrated into a trough-shaped reflector 29 andthe line of light emitting diodes 10 into a trough-shaped reflector 30.The two reflectors 29, 30 are separated from one another so that theerasing light emitted by the lines of light emitting diodes 9, 10 hitsthe storage phosphor layer located in the erasing apparatus separately.The lines of light emitting diodes 9, 10 emit erasing light in differentwavelength ranges. The line of light emitting diodes 9 emits erasinglight in the blue wavelength range, and the line of light emittingdiodes 10 in the red wavelength range. In this way good “colorseparation” and so a high level of erasing efficiency can advantageouslybe achieved. Therefore, in the direction of conveyance 6 of the storagephosphor plate first of all blue and then red erasing light hits thestorage phosphor layer. Furthermore, the intensity of the longerwavelength or longwave, red erasing light is greater than the intensityof the shorter wavelength or shortwave, blue erasing light. Theintensity portion of the red erasing light is advantageously approx. 66%here, and the intensity portion of the blue erasing light is approx.33%. In this way, particularly good erasing efficiency is guaranteed.

In order to guarantee particularly efficient color separation, it can beadvantageous for at least one of the reflectors 29 or 30 to be designedasymmetrically such that the flank of the respective reflector troughfacing towards the respective other reflector 30 or 29 has an innerangle which is smaller than that of the flank facing away from therespective other reflector 30 and 29.

In order to further improve the erasure efficiency, it is possible toprovide additional optics on the radiation source 8, i.e. in particularon the lines of light emitting diodes 9, 10, which reduce the emissionangle of the light emitting diodes. In this way the irradiated surfaceon the storage phosphor layer 2 can be narrower in form. This increasesthe power density for the erasure.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. An apparatus for erasing a storage phosphor layer, comprising: aradiation source for producing and emitting erasing radiation, a drivefor producing a relative movement between the storage phosphor layer andthe radiation source, the storage phosphor layer lying or being moved ina holding plane, and a reflector for reflecting radiation that isarranged to reflect erasing radiation reflected by the storage phosphorlayer in the direction of the storage phosphor layer, and a furtherreflecting surface for reflecting erasing radiation, the furtherreflecting surface being positioned opposite the reflector, whenconsidered in a direction at right angles to the direction of therelative movement.
 2. The apparatus according to claim 1, wherein thefurther reflecting surface is disposed on the side of the holding planefacing away from the reflector.
 3. The apparatus according to claim 1,wherein the further reflecting surface has a width in the direction ofthe relative movement which is at least as great as that of thereflector.
 4. The apparatus according to claim 1, wherein a width of thereflector in the direction of the relative movement is at least tentimes as great as a smallest distance between the reflector and theholding plane.
 5. The apparatus according to claim 1, wherein thereflector has a flat reflector surface that extends parallel to theholding plane.
 6. The apparatus according to claim 1, wherein thereflector has a reflector surface with a structure.
 7. The apparatusaccording to claim 1, wherein the reflector has at least two reflectorsurfaces so that the reflector, when considered in the direction of therelative movement, is positioned to either side of the radiation source.8. The apparatus according to claim 1, wherein the reflector has agroove- or trough-shaped cross-sectional surface.
 9. The apparatusaccording to claim 8, further comprising, when considered in thedirection of the relative movement, reflector extension surfacesextending parallel to the holding plane that adjoin both ends of thegroove.
 10. The apparatus according to claim 9, wherein the reflectorextension surfaces have structures.
 11. The apparatus according to claim1, wherein the radiation source has at least two lines with lightemitting diodes extending at right angles to the direction of therelative movement and parallel to the holding plane.
 12. The apparatusaccording to claim 11, further comprising a particular reflector that isallocated to each of the at least two lines with light emitting diodes,and the light emitting diodes of the respective lines emit radiation ina narrow-band wavelength range that is different that that of the lightemitting diodes of the other lines.
 13. A system, comprising: a storagephosphor layer; and an apparatus for erasing the storage phosphor layer,comprising: a radiation source for producing and emitting erasingradiation, a drive for producing a relative movement between the storagephosphor layer and the radiation source, the storage phosphor layerlying or being moved in a holding plane, and a reflector for reflectingradiation that is arranged to reflect erasing radiation reflected by thestorage phosphor layer in the direction of the storage phosphor layer,and a further reflecting surface for reflecting erasing radiation, thefurther reflecting surface being positioned opposite the reflector, whenconsidered in a direction at right angles to the direction of therelative movement.
 14. The system according to claim 13, wherein thestorage phosphor layer has a degree of reflection for the erasingradiation of greater than or equal to 70%.
 15. The system according toclaim 13, wherein the storage phosphor layer has a degree of reflectionfor the erasing radiation of greater than or equal to 80%.
 16. A methodfor erasing a storage phosphor layer, comprising: producing and emittingerasing radiation toward the storage phosphor layer, producing arelative movement between the storage phosphor layer and a radiationsource producing the erasing radiation, the storage phosphor layer lyingor being moved in a holding plane, and reflecting erasing radiation thatwas reflected by the storage phosphor layer in the direction of thestorage phosphor layer, and further reflecting the erasing radiationback from the holding plane in a direction of the radiation source.